I started playing this past weekend. I’ve had no crash problems except for a mod I tried. Yesterday’s patch has some weirdness too it, but nothing too severe. Note, though, my tolerance for bugs is much higher than the average person I reckon.
The changes are not surprisingly substantial. For civilized nations, only slaves can manually be moved now. Tribes can still move tribesman. There’s a host of buildings and city improvements to manage migration, promotions, assimilation and conversions. The result is a more organic change, but it can be at the same time quite slow. It makes for colonizing new lands a very long term affair if playing near frontier regions (e.g. the Bosporus Kingdom.) The move away from ‘mana’ is overall a positive one I think as there is less reliance on good monarchs to progress. I do quite like the internal management options as I tend to play tall-ish more than paint the map (you can now easily move province and kingdom capitals, yay.) Map painters I don’t think need worry too much about that though aside from queuing up buildings to maintain tech advancement (libraries, academies.) For large nations with “mega” cities, food management might become an issue, but I don’t have any direct experience with that as yet.
Oh, there’s some more flavor now too between different regions and countries. There are a lot of generic ‘traditions’, but some more notable nations have specific ones (much like back in the day when EU4 first adopted them.) The AI seems improved too (Carthage actually expands now, as does Rome.)